PostgresQL 学习记录之与oracle区别(二)
(9)字段取别名必须用as
Oracle -- SELECT A.COL1 A_COL1,A.COL2 A_COL2 FROM A_TABLE A
Postgresql---- SELECT A.COL1 AS A_COL1,A.COL2 AS A_COL2 FROM A_TABLE A
(10)NVL用法
Oracle --SELECT NVL(SUM(VALUE11),0) FS_VALUE1, NVL(SUM(VALUE21),0) FS_VALUE2 FROM FIELD_SUM
Postgresql--SELECT COALESCE(SUM(VALUE11),0) AS FS_VALUE1,COALESCE(SUM(VALUE21),0) AS FS_VALUE2
FROM FIELD_SUM
(11)TO_NUMBER用法
Oracle -- SELECT COL1 FROM A_TABLE ORDER BY TO_NUMBER(COL1)
Postgresql- select TO_NUMBER(COL1,'99G999D9S') from A_TABLE [注:'999999' ---- 6位数为COL1字段的长度]
(12)DECODE用法
Oracle -- SELECT DECODE(ENDFLAG,'1','A','B') ENDFLAGFROM TEST
Postgresql- SELECT (CASEENDFLAG WHEN '1' THEN 'A'ELSE 'B' END) AS ENDFLAG FROM TEST
(13)统计 相关 用法
Oracle -- SELECT ROUND(AVG(SUM(BASICCNT1))) BASICCNT FROM ACCESS_INFO_SUM1_V
WHERE YEARCODE BETWEEN '200305' AND '200505' GROUP BY SCCODE
Postgresql-- SELECT ROUND(AVG(AIV.BASICCNT)) AS BASICCNT FROM ( SELECT SUM(BASICCNT1) AS BASICCNT
FROM ACCESS_INFO_SUM1_V WHERE YEARCODE BETWEEN '200305' AND '200505' GROUP BY sccode ) AIV
(14)时间计算 用法
Oracle -- SELECT CEIL(SYSDATE - TO_DATE('20051027 14:56:10','YYYYMMDD HH24:MI:SS')) AS DAYS
FROM DUAL
Postgresql-- SELECT EXTRACT(DAY FROM (TO_TIMESTAMP(CURRENT_TIMESTAMP,'YYYY-MM-DD-HH24-MI-SS') - TO_TIMESTAMP('2005-10-27 14:56:10','YYYY-MM-DD-HH24-MI-SS') ))+1 AS DAYS FROM DUAL
Oracle -- add_months(date, int)
Postgresql--创建函数来解决
CREATE FUNCTION add_months(date, int)
RETURNS date AS
'SELECT ($1 + ( $2::text || ''months'')::interval)::date;'
LANGUAGE 'sql'
阅读更多
- Oracle SQL脚本学习记录二
- Oracle学习记录1(单行函数,多行函数)
- Oracle学习记录2(多表查询)
- oracle学习.oracle中全局数据库名和SID的区别
- 记录学习的点滴(MyBatis中#{}与${}区别)
- oracle学习记录之错误
- Oracle-01-学习内容&安装遇到的问题记录
- oracle sql 学习记录
- PostgreSQL infomask/infomask2 学习记录
- Oracle 11g 从入门到精通学习记录
- Oracle SQL脚本学习记录三
- oracle和sql server取第一条记录的区别以及rownum详解
- Oracle学习记录整理笔记2-用户管理
- Oracle学习记录1(单行函数,多行函数)
- Oracle学习记录2(多表查询)
- JAVA_WEB Oracle 10g学习: PL/SQL集合与记录
- oracle学习记录之授权(2)
- 工作学习记录--angularjs 中的$watch与$observe监听区别
- Oracle SQL脚本学习记录四
- Oracle学习记录1(单行函数,多行函数)